1. Field of the Invention
The present invention relates to a polymethylaluminoxane preparation used as a catalyst for polymerization of olefins, and a production method thereof, a polymerization catalyst using the polymethylaluminoxane preparation as a catalytic component, and a polymerization method of olefins.
2. Description of the Related Art
Aluminoxane is a condensation product, generally prepared by a partial hydrolysis of an organic aluminum compound, and known to be useful as a promoter component that efficiently activates a transition metal compound which is a main catalyst. It is widely known that a polymethylaluminoxane preparation prepared by using trimethylaluminum as an organic aluminum compound, a raw material thereof, in particular, exhibits an excellent promoter performance. Examples can be found, for example, in (Patent document 1), (Patent document 2), (Patent document 3), (Patent document 4), (Patent document 5), (Patent document 6), and the like.
Up to know, many proposals have been made regarding production of a polymethylaluminoxane preparation. A first exemplary proposal involves controlling reaction between water and trialkylaluminum using an inorganic salt having water of crystallization such as copper sulfate or aluminum sulfate. Examples of such proposal include (Patent document 7), (Patent document 8), (Patent document 9), and (Patent document 10). In these proposals, it is necessary to grind a solid inorganic salt into adequately fine particles in order to efficiently use the water of crystallization, and long reaction time is required. Furthermore, a large part of the generated polymethylaluminoxane preparation is adsorbed to the inorganic salt, so that the yield is greatly reduced.
A second exemplary proposal for the production method of polymethylaluminoxane preparation involves adding water that is finely dispersed in an inert solvent, to trimethylaluminum dissolved and diluted in an inert solvent. Examples of such proposal include (Patent document 11), (Patent document 12), (Patent document 13), (Patent document 14), and (Patent document 15). In the reaction between water and trimethylaluminum, however, since solid or gel is inevitably formed as one form of trimethylaluminum having excessively hydrolyzed, the reaction yield based on aluminum is decreased. Also found is an attempt to suppress generation of solids or gels by conducting hydrolysis in an extremely low concentration and controlling the degree of hydrolysis of trialkylaluminum relatively to low. However, such preparation method will lead significant decrease in generation efficiency of the polymethylaluminoxane preparation.
T. Mole et al. have reported that a polymethylaluminoxane preparation can be obtained by thermal decomposition of an aluminum alkoxide compound that is generated by a reaction between trimethylaluminum and an oxygen-containing compound such as tertiary alcohols, ketones, and carboxylic acids. Examples of such report include (Non-patent document 1), (Non-patent document 2), and (Non-patent document 3). The methylaluminoxane preparation prepared in this manner is described in (Non-patent document 4) as being unsuited for a promoter of a transition metal complex which is a main catalyst for polymerization of olefins, and hence the above method was not recognized as a useful preparation method of polymethylaluminoxane.
According to a description of (Patent document 7) by G. M. Smith et al., nonhydrolytic conversion of a precursor for polymethylaluminoxane formed by treating trialkylaluminum with an organic compound having a carbon-oxygen bond gives a polymethylaluminoxane preparation essentially containing no trimethylaluminum, and the polymethylaluminoxane preparation thus obtained is catalytically useful. The term “nonhydrolytic conversion” normally means thermal decomposition reaction. It is also described that addition of a Lewis acid such as polymethylaluminoxane preparation promotes the thermal decomposition reaction and reduces the time required for the thermal decomposition. As the reports regarding this concept, (Patent document 16) and (Non-patent document 5) can be recited. (Non-patent document 5) discloses that, as a catalyst for thermal decomposition, polymethylaluminoxane preparation and aluminum chloride have excellent catalytic actions. However, when a nonhydrolytically prepared polymethylaluminoxane preparation is used as a catalytic component for polymerization of olefins, use of a halogen-containing alkyl aluminum such as aluminum chloride is a direct cause of decrease in polymerization activity. The approach of using a polymethylaluminoxane preparation as a catalyst for thermal decomposition imposes one of limitations in practical production of polymethylaluminoxane preparation. One problem lies in that due to trimethylaluminum essentially contained in a polymethylaluminoxane preparation as a raw material, when one determines a quantity ratio between trimethylaluminum and an oxygen-containing compound, some error occurs in the set value depending on the composition and amount of the added polymethylaluminoxane preparation. Therefore, compounds that have been known heretofore as a catalyst for thermal decomposition are not favorable from the view point of industrial production of polymethylaluminoxane preparation.
S. A. Sangokoya et al. report in (Patent document 17) that nonhyrolytic conversion of the above polymethyl aluminoxane precursor is promoted by adding a catalytic amount of water. This proposal solves a part of problem caused by addition of polymethylaluminoxane as a catalyst for thermal decomposition. However, if the added amount of water is excess in the case of adopting the nonhydrolytic preparation method of polymethylaluminoxane, gels are formed to lower the yield.
[Patent document 1] Japanese Patent Laid-Open Publication No. Sho 58-19309
[Patent document 2] Japanese Patent Laid-Open Publication No. Sho 60-35005
[Patent document 3] Japanese Patent Laid-Open Publication No. Sho 62-234009
[Patent document 4] Japanese Patent Laid-Open Publication No. Sho 63-234009
[Patent document 5] Japanese Patent Laid-Open Publication No. Sho 64-66214
[Patent document 6] Japanese Patent Laid-Open Publication No. Hei 1-207355
[Patent document 7] Description of U.S. Pat. No. 4,404,344
[Patent document 8] Description of U.S. Pat. No. 4,544,762
[Patent document 9] Description of U.S. Pat. No. 4,665,208
[Patent document 10] Japanese Patent Laid-Open Publication No. Hei 1-258686
[Patent document 11] Description of U.S. Pat. No. 4,730,071
[Patent document 12] Description of U.S. Pat. No. 4,730,072
[Patent document 13] Japanese Patent Laid-Open Publication No. Hei 2-219805
[Patent document 14] Description of U.S. Pat. No. 5,103,031
[Patent document 15] Japanese Patent Laid-Open Publication No. Hei 4-235990
[Patent document 16] Pamphlet of WO 97/23288
[Patent document 17] Description of U.S. Pat. No. 6,013,820
[Non-patent document 1] Australian Journal of Chemistry 27, 1639 (1974)
[Non-patent document 2] Australian Journal of Chemistry 27, 1655 (1974)
[Non-patent document 3] Australian Journal of Chemistry 27, 1665 (1974)
[Non-patent document 4] Comprehensive Organometallic Chemistry II, 1, 452 (1995)
[Non-patent document 5] Organometallics, 20, 5162 (2001)